Functional fluids comprising alkyl toluene sulfonates

ABSTRACT

Provided are formulations, methods of making, and methods of using a functional fluid of the present invention to achieve and maintain optimal frictional characteristics in machines housing that fluid, wherein the functional fluid comprises, among others, a friction-modifying amount of an alkyl toluene sulfonate salt or a mixture of alkyl toluene sulfonate salts.

The present invention relates to functional fluid compositions suitablefor use in systems and machines comprising relatively moving andcoupling parts. In particular, the present invention relates tofunctional fluid compositions suitable for use in heavy machinery,especially in high-power-output tractors, transmissions, hydraulics, andthe like. The present invention further pertains to a new and improvedclass of friction modifying agent that can be used to render suchfavorable frictional characteristics to functional fluids. Moreover, thepresent invention is concerned with methods of providing optimalfrictional characteristics to machines housing the functional fluids andmaintaining such characteristics therein. Furthermore, the presentinvention relates to the methods of preparing such functional fluidcompositions.

The term “functional fluids” encompasses various types of fluids,including for example, tractor fluids, automatic transmission fluids,manual transmission fluids, hydraulic fluids, power steering fluids,fluids for use with power-train components, as well as fluids of variousother capacities. These fluids typically do more than merely lubricatingthe machines that house them. Rather, they provide one or morefunctionalities other than, or in most cases, in addition to, lubricity.The additional functionalities may enable the machines to operate moreeffectively and/or efficiently. Therefore, functional fluids tend to bemulti-functional fluids, although at least one of their functions istypically related to providing lubrication to the machine componentsimmersed therein.

The several functions and characteristics of the functional fluids arebestowed upon the functional fluids by additives. Typical additives forfunctional fluids may include, for example, viscosity index improvers,oxidation inhibitors corrosion/rust inhibitors, dispersants, pour pointdepressants, foam inhibitors, demulsifiers, antiwear agents, sealswellants, friction modifiers, and others. The present invention relatesto a new class of friction modifiers.

Although persons skilled in the art often use the terms “frictionmodifying agent” and “friction modifier” interchangeably, for thepurpose of the present invention, a friction modifying agent may referto a material that is other than a conventional friction modifier.Rather, the term “friction modifying agent” refers to any agent thatmodifies or affects the friction properties of a fluid to which it is apart. The textbook, LUBRICANT ADDITIVES, CHEMISTRY & APPLICATIONS,Rudnick, ed, (Marcel Decker Inc., New York) (2003), defines friction atpage 204, as “the resistance a body meets while moving over another bodyin respect of transmitting motion.” In conventional lubricating oilcompositions, friction modifiers are known to simply reduce the frictionbetween surfaces that come into contact with each other duringoperation, thus reducing wear to these surfaces. Specifically, as thesurfaces move closer together, the lubricant is squeezed out betweenthem. During this process, the friction modifiers in the lubricantbecome adsorbed onto the surfaces, thereby retained between thesurfaces, displaying a molecular orientation perpendicular to thesurfaces to reduce the level of contact and lower the friction. Incomparison, friction modifying agents typically do more than reducingfriction in functional fluids. These fluids are used with relativelymoving and coupling parts that are at least partially immersed therein.These fluids thus must keep the friction levels at an optimal level,sufficiently low to prevent excessive wear and tear, but alsosufficiently high so that the relatively moving and coupling parts mayaccurately engage and disengage without slippage.

Functional fluids are therefore formulated to meet both the operationaland the lubrication needs of the machines. For example, tractor fluidsare used to lubricate the transmissions, gears, bearings, hydraulics,power steering components, mechanical power takeoffs, and oil-immersedbrakes in machines driven by tractors. When a functional fluid is usedto lubricate the hydraulics in a tractor, it may also be called atractor hydraulic fluid. Used in a tractor, a functional fluid mayprovide for brake capacity, engagement and disengagement of powertakeoff clutches, and transfer and dissipation of heat generated duringoperation. In modern tractors, power brakes can either be of thedrum-type or the disc-type, but the disc-type brakes are preferredbecause of their superior braking capacity. Further among the discbrakes, the wet-type or oil-immersed brakes are preferred because thefunctional fluids effectively isolate the brakes from dirt and grime.Despite these known advantages of wet disc brakes, they often suffer atleast one prominent drawback, namely, brake chatter (also known as brakesquawk). Brake chatter occurs where the torque variation of the frictionmaterial or reaction plate is so large as to create harmonic vibrationsin the equipment. These vibrations usually lead to objectionable andunpleasant sounds being emitted from the equipment when brakes areapplied.

To combat brake chatter, persons skilled in the art have, for example,added friction modifiers such as dioleylhydrogen phosphite to tractorfluids or tractor hydraulic fluids. Often, however, these conventionalfriction modifying agents would render the fluids unsuitable for use forvarious reasons. First, brake chatter is but one of the many issues thatmust be addressed when formulating a tractor fluid or a tractorhydraulic fluid. For example, the capacities of both the wet brakes andthe power takeoff clutches are always considered. Conventional frictionmodifiers such as dioleyhydrogen phosphite, while effective in reducingthe brake chatter, can be associated with an unacceptable simultaneouslowering of the brake and takeoff clutches capacities, making it moredifficult to engage the clutches and/or bring the equipment to stop.Therefore, although a suitable friction modifying agent should reducefriction, it should only do so to a certain extent rather than as muchas possible. The resulting friction level is preferably one at which acompromise is reached to minimize brake chatter while maintaining thebrake/clutch capacities. Accordingly, a suitable tractor fluid ortractor hydraulic fluid would pass both a wet brake chatter test and awet brake capacity test. Second, because many tractor parts other thanthe brake discs are exposed to the same fluid, a suitable tractor fluidor tractor hydraulic fluid would lubricate these non-brake parts andprovide power and means to dissipate heat. As a result, many knownfriction modifiers cannot be used in tractors because of their inabilityto provide adequate lubrication to or otherwise protect the non-brakeparts. For instance, fluids containing dioleylhydrogen phosphite are notused in tractors because the additive is known to give rise to high gearwear, particularly when the gears are used at high temperatures.Furthermore, an apt functional fluid for use in tractors must offerextreme-pressure properties and certain other capacities such aswater-tolerance or filterability. Therefore, to qualify as a tractorfluid or tractor hydraulic fluid, a given functional fluid must passtests besides the wet brake chatter and capacity tests mentioned above.Such additional tests may include, for example, a spiral bevel test anda straight spur gear test, each giving indications of extreme-pressureproperties.

Transmission fluids constitute another prominent group of functionalfluids. An automatic transmission comprises a turbine drive unit, atorque converter, and one or more friction brakes or clutches that areengaged and disengaged automatically by an intricate hydraulic controlunit. A manual transmission comprises a similar set of components, butthe one or more friction brakes or clutches are engaged and disengagedmanually. A typical but simplified clutch assembly comprises plain steelplates that come into contact with other steel plates, the latter platesbeing covered on both sides with a friction material, such as, forexample, compressed paper impregnated with a resin. There are manysimilarities between a clutch assembly of a transmission and a set ofdisc brakes of a tractor. For example, here the entire clutch assemblyis immersed completely or partially in the transmission fluid, just asthe disc brakes are immersed completely or partially in the tractorhydraulic fluid. Accordingly, like their tractor hydraulic fluidscounterparts, transmission fluids are typically multi-functional fluids.They lubricate the gears and hearings, transfer heat, and provide thefluids for hydraulic control and power transfer. Specifically, asuitable transmission fluid provides sufficient friction for the clutchplates to transfer power, allowing the transmission to shift smoothlyand allowing it to lock up during a shift from one speed to anotherwithin a certain specified period of time, but not too much friction tocause wear and tear of bearing surfaces and the clutch plates.

Several parameters are used by persons skilled in the art to evaluatecompositions for suitability as transmission fluids. Those parameterscan be used individually or in combination with each other. One of thoseparameters is static or breakaway torque (T_(s)), which measures therelative tendency of engaged parts such as clutch packs, to slip underload. T_(s) is typically determined upon completion of certainpredetermined cycles of dynamic torque evaluation sequence. The use ofconventional friction modifiers in attempts to improve frictionalstability may reduce this breakaway T_(s) to levels that are too low, atwhich the relative tendency of engaged parts to slip under load becomeunacceptable. That slippage can impair the drivability and safety of thevehicle to which tile transmission is a part. Another often-usedparameter, the “lock-up,” measures the tendency of the clutch to graband release intermittently when operating at relatively low slidingclutch speeds at which the clutch pack is fully engaged, causingstick-slip or shudder in the automobile. Yet another parameter is die“break-in period,” which measures the change in frictional performanceover time. It is desirable to have a friction modifying agent that doesnot exhibit a break-in period or that has a very short break-in period.Persons skilled in the art also use other parameters, some of which arederived from the three parameters above, to assess the frictionalcharacteristics of transmission fluids.

Further examples of functional fluids include, for example, hydraulicfluids, which embody a similar set of multi-faceted considerations. Onetype of hydraulic fluid is the tractor hydraulic fluid, which isdiscussed above along with various other functional fluids suitable foruse in tractors. Aside from the usual lubricant additives such as, forexample, antioxidants, corrosion inhibitors, foam inhibitors, anti-wearagents, viscosity index improvers, pour point depressants, detergentsand dispersants, and seal swellants, friction modifying agents aretypically employed in these fluids to promote smooth and sticking-and/or slipping-free operation of me hydraulic systems. Indeed,hydraulic fluids typically require the inclusion of friction modifyingagents to function properly. The need for friction modifying agentsbecomes especially acute when the relative motions betweenheavily-loaded mating surfaces are slow. This is because, as therelative speed between two contacting surfaces diminishes, the lubricantfilm thickness also decreases, resulting in increased physical contact,higher friction, and higher wear of the surfaces. Friction modifyingagents are also typically used when there are exacting accuracyrequirements for the coupling process, such as for example, innumerically controlled machine tools, or when the coupling surfaces aremade of different materials. Moreover, the initial friction is usuallyhigh in hydraulic systems, because surface asperities must be liftedover one another until sufficient speed is achieved to establish acontinuous hydrodynamic lubricating film that separates the couplingsurfaces. Therefore, a suitable hydraulic fluid not only lubricates thehydraulic elements, but also achieves and maintains an optimal level offriction among the coupling surfaces so as to prevent uneven operationunder various speeds, loads, and material combinations.

Accordingly, a suitable functional fluid would provide a level offriction that is neither too low for the accurate engagement anddisengagement of relatively moving parts, nor too high so that therewould be an unacceptable level of wear and tear. The present inventionprovides such a friction modifying agent, which imparts improvedfrictional characteristics to various functional fluids.

A typical friction modifying agent may be a long-chain moleculecomprising a polar end group and a non-polar linear hydrocarbon chain.The polar end group either physically-adsorbs onto a metal surface,chemically reacts with the surface, or otherwise attach to the surface,while the hydrocarbon chain extends into the functional fluid. Chainsfrom multiple friction modifying molecules men link with one another andwith the other components in the fluid to form a film on the metalsurface.

Persons skilled in the art are aware that many friction modifierssuitable for use in conventional lubricating oils are often nonethelessunsuitable for use in functional fluids because the latter have moredemanding functional and compatibility requirements. As discussed above,for use in functional fluids, a friction modifying agent must be capableof reducing friction, but only to a certain extent so as to achieve theleast possible wear without sacrificing smooth and accurate operation.Furthermore, some conventional friction modifiers are known tochemically or physically interact with other additives that arenecessarily or optionally included in the functional fluids, effectivelycompeting with these other additives for occupation of the surfaces onthe moving metal parts.

There have been sustained efforts in the art to develop new frictionmodifying agents suitable for use in various functional fluids. A fewagents have been identified to date and some of those are describedbelow. There nonetheless remains a significant need for alternativesand/or improvements.

A number of the friction modifiers identified as suitable for use infunctional fluids are amines, amides, or other nitrogen-containingcompounds, which would, among other things, raise the nitrogen contentof the fluids and restrict their potential scopes of application as aresult. For example, U.S. Pat. No. 3,634,256 disclosed an automatictransmission fluid containing (1) a friction modifier selected from thegroup consisting of oxyalkylated aliphatic tertiary amines,1-hydroxyalkyl-2 alkyl imidazolines (e.g.,1-hydroxyethyl-2-heptacecyl-2-imidazoline) and mixtures thereof; and (2)an oil-soluble polyalkenyl substituted succinimide of an alkylenepolyamine. U.S. Pat. No. 3,933,659 disclosed another automatictransmission fluid comprising a major amount of an oil of lubricatingviscosity, and an effective amount of each of the following: (1) analkenyl succinimide; (2) a Group II metal salt of a dihydrocarbyldithiophosphoric acid; (3) a friction-modifying compound selected fromthe group consisting of: (a) fatty acid esters of dihydric and otherpolyhydric alcohols, and oil soluble oxyalkylated derivatives thereof,(b) fatty acid amides of low molecular weight amino acids, (c) N-fattyalkyl-N,N-diethanol amines, (d) N-fattyalkyl-N,N-di-(ethoxyethanol)amines, (e) N-fattyalkyl-N,N-di-poly-(ethoxy)ethanol amines, and (f) mixtures thereof; and(4) a basic sulfurized alkaline earth metal alkyl phenate. Thiscomposition was indicated to be particularly suitable for use withautomatic transmissions of passenger cars. More recently, U.S. Pat. No.6,803,350 disclosed a tractor fluid comprising a friction-modifyingamount of an oil-soluble fatty acid amide and a fatty acid ester derivedfrom a polyhydric alcohol. That tractor fluid was said to exhibit goodanti-chatter characteristics.

The art also taught the use of several metal salts of fatty hydrocarbylsulfonates as friction modifiers in functional fluids. For example, U.S.Pat. No. 3,410,801 described a hydraulic fluid suitable for use in a wetclutch system comprising a friction-modifying amount of the reactionproduct of an overbased metal hydrocarbon sulfonate and a fatty acid.Recently, U.S. Pat. No. 7,012,045 disclosed the use of polyalkenylsulfonates in functional fluids to provide improved brake and clutchcapacity, wherein the polyalkenyl sulfonate was an alkali metal oralkaline earth metal salt of a polyalkene sulfonic acid derived from amixture of polyalkenes comprising greater than about 20 mole percentalkyl vinylidene and 1,1-dialkyl isomers.

On occasion, aromatic hydrocarbyl sulfonate salts have been used tomodify friction in certain functional fluids. For example, U.S. Pat. No.3,451,930 taught a fluid for farm tractor transmissions comprising afriction modifier that was a three-component mixture of (1) a metal saltof a hydrocarbon sulfonic acid, which may be a metal salt of an aromatichydrosulfonic acid or a metal salt of a non-aromatic hydrosulfonic acid;(2) a zinc salt of a dialkyl dithiophosphoric acid; and (3) achlorinated paraffin wax. Moreover, U.S. Pat. No. 3,259,583 disclosedpower transmission fluid consisting essentially of a major amount of amineral lubricating oil, and a small amount of a friction modifier thatwas another three-component mixture of (1) an overbased alkaline earthmetal petroleum sulfonate, which may be an aromatic sulfonate or anon-aromatic sulfonate; (2) a polyaryl polyamine having the formula:

wherein X is oxygen, sulfur, or a methylene radical and R is a C₁ to C₈alkyl radical such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl,t-butyl, amyl, hexyl, octyl radical; and (3) a zinc salt of anunsaturated fatty acid having from 12 to 18 carbon atoms. According tothat patent, all three parts must be included to affect the frictionalcharacteristics of the fluid, because “none of these materials alonepossess[es] anti-frictional properties and yet in combination they areexcellent friction inhibitors.”Column 1, lines 60-62.

On the other hand, aromatic hydrocarbon sulfonates such as alkyl arylsulfonates have been widely applied as detergents or dispersants infunctional fluids. For example, U.S. Pat. No. 3,899,432 disclosed afunctional fluid comprising an oil of lubricating viscosity, and aneffective amount of each of (1) Group II salt, of hydrocarbyl sulfonicacid; (2) overbased group II metal salt of hydrocarbyl sulfonic acids;(3) Group II salt of dihydrocarbyl dithiophosphoric acid; (4) tricresylphosphate; and (5) sulfurized mixture of olefins and fatty acid esters.The neutral sulfonate salts were said to provide improved watertolerance, detergency and dispersancy, whereas the overbased sulfonatesalts were said to improve thermal stability, antioxidation, and rustinhibition. Similarly, U.S. Pat. No. 3,920,562 disclosed a functionalfluid especially suitable for use as an automatic transmission fluidcomprising a major amount of an oil of lubricating viscosity, and aneffective amount of each of (1) an alkynyl succinimide; (2) a group IImetal salt of a dihydrocarbyl dithiophosphoric acid; (3) a hydroxylfatty acid ester of dihydroic or polyhydric alcohol or oil-solublealkyoxylated derivatives thereof; and (4) a group II metal salt of ahydrocarbyl sulfonic acid “act[ing] as a detergent and dispersant,” to“prevent the deposit of contaminants formed during high temperatureoperation of the system containing the functional fluid.” Column 7, line66, to column 8, line 2. In yet another example, U.S. Pat. No. 4,253,977disclosed a functional fluid with improved static friction behavior overextended period of time, comprising an overbased alkali or alkalineearth metal salt of a hydrocarbyl sulfonic acid, an alkyl phenate, or asulfurized alkyl phenol as a detergent. That particular functional fluidcomposition also comprised a friction modifier that was either an alkylor alkyenyl C₄ to C₁₀ dicarboxylic acid having about 6 to 30 carbonatoms, or the reaction product of long-chain dicarboxylic anhydride withan aldehyde/tris-hydroxymethyl aminomethane adduct.

Overbased alkyl aryl sulfonates were also known to impart improvedcompatibility, solubility, foaming properties, low color, and minimalskin formation, for example, in U.S. Pat. No. 6,479,440. A mixture ofalkyl phenyl sulfonates of alkaline earth metals comprising 50 to 85% oflinear mono-alkyl phenyl sulfonate and 15 to 50% of a heavy alkyl arylsulfonate was reported to have good solubility, stable (i.e., no skinformation) at room temperature, and have otherwise gooddetergent/dispersant performance in U.S. Pat. No. 6,054,419. The heavyalkyl aryl sulfonates of that patent include two types: (1) dialkyl arylsulfonates, wherein the two alkyl groups are both linear; and (2) monoor poly alkyl aryl sulfonates, wherein the alkyl substituents arebranched chains of certain lengths. A slightly modified mixture ofalkaline earth metal alkyl phenyl sulfonates was said to have improvedcharacteristics as a detergent and/or dispersant in a companion EuropeanPatent Application No. 98401968.7. That modified mixture comprised 20 to70% of a linear mono alkyl phenyl sulfonate and 30 to 80% of a branchedmono alkyl phenyl sulfonate.

Alkyl aryl sulfonates have also found occasional use as load-capacityimprovers. For example, U.S. Pat. No. 3,451,930 disclosed a high-loadgear oil especially suitable for use in rear axles and tractortransmissions. The high-load formulation was developed following theunexpected finding that a combination of three components: (1) analkaline earth metal salt of a hydrocarbon sulfonic acid having amolecular weight of about 400 to about 900; (2) a metal salt of adialkyl dithiophosphoric acid; and (3) a chlorinated hydrocarbon;exerted a synergestic improvement in the load-carrying capacity.

We have found that certain alkyl toluene sulfonate salts possessdesirable frictional properties and may serve as friction modifyingagents in functional fluids. The alkyl toluene sulfonate salt or amixture of these salts of the present invention may or may not be theonly friction modifying agent in a particular functional fluid. Forexample, an alkyl toluene sulfonate salt or a mixture of salts of thepresent invention may be used as the sole friction modifying agent in agiven functional fluid, or it may be used in conjunction with one ormore other compatible friction modifiers to provide the desired level offriction for that particular fluid. The present invention provides suchalkyl toluene sulfonates, as well as functional fluid compositionscomprising these sulfonates. The present invention further providesmethods for preparing these functional fluids and using them to affectthe friction levels among relatively moving and coupling parts incertain machines.

SUMMARY

The present invention relates to a class of new and improved frictionmodifying agents suitable for use in functional fluids, especially intractor fluids, tractor hydraulic fluids, transmission fluids, hydraulicfluids, and the like. Specifically, the friction modifying agents of thepresent invention comprise alkyl toluene sulfonate salts. In someembodiments of the present invention, the alkyl toluene sulfonate saltsare prepared by first alkylating toluene with isomerized olefins, thensulfonating the alkylated toluenes, followed by the introduction ofmetal sources. The alkyl toluene sulfonate salts of the presentinvention and mixtures thereof provide improved frictionalcharacteristics to the functional fluids. Furthermore, thefriction-modifying capacity of the alkyl toluene sulfonate salts of thepresent invention is not substantially diminished by the presence ofchloride ions, which are sometimes introduced into the functional fluidsby, for example, certain viscosity modifiers used in the manufacturingprocesses. Thus, the functional fluids of the present invention can beused in the presence of chloride ions.

The first aspect of the present invention pertains to a frictionmodifying agent suitable for use in a functional fluid. The frictionmodifying agent of this aspect comprises an alkyl toluene sulfonatesalt.

The second aspect of the present invention pertains to a functionalfluid composition with improved frictional properties comprising afriction modifying agent of the first aspect. The functional fluid ofthis aspect is especially suitable for use as a tractor fluid, a tractorhydraulic fluid, a transmission fluid, or a hydraulic fluid, but mayalso be used in other machines comprising relatively moving and couplingparts.

The third aspect of the present invention pertains to a functional fluidof the second aspect, comprising a friction modifying agent of the firstaspect, the friction-modifying capacity of which is not substantiallydiminished in the presence of chloride ions.

The fourth aspect of the present invention pertains to a frictionmodifying agent of the first aspect, the friction-modifying capacity ofwhich is not substantially diminished in the presence of chloride ions.

This invention, in its fifth aspect, provides a method of making afunctional fluid of the second and third aspects.

In its sixth aspect, this invention, also pertains to a method ofproviding and maintaining optimal levels of friction in machinescomprising relatively moving and coupling parts by applying thefunctional fluid of the second or third aspect.

Persons skilled in the art will understand other and further objects,advantages, and features of the present invention by reference to thefollowing description.

DETAILED DESCRIPTION

Various preferred features and embodiments are described below by way ofnon-limiting illustrations.

The present invention relates to a functional fluid compositioncomprising one or more alkyl toluene sulfonate salts as frictionmodifying agents. Specifically, the alkyl toluene sulfonate salts of thepresent invention are salts of oil-soluble alkyl toluene sulfonic acids.The alkyl toluene sulfonate salts of the present invention may be anytype of metal salts, including alkaline earth metal salts, alkali metalsalts, and the like. An exemplary group of alkyl toluene sulfonate saltsof the present invention are calcium salts. Moreover, the salts of thepresent invention are often overbased salts, although neutral salts arealso acceptable. The salts of the present invention may further beoverbased with carbon dioxide. The one or more alkyl toluene sulfonatesalts of the present invention may be derived from alkyl toluenealkylates that are the alkylation products of toluene and linearolefins. As it is understood by persons skilled in the art and forpurpose of the present invention, the term “a linear olefin” refers to anon-cyclic olefin. Accordingly, the linear olefin used to alkylate thetoluene can be branched or unbranched. Furthermore, the linear olefinused to alkylate the toluene can be either a single olefin or a mixtureof olefins with varying numbers of carbon atoms. The single olefinand/or the olefins in tire mixtures are preferably selected from C₁₈ toC₃₀ linear olefins. Regardless of the length of the chains, or whetherthe alkylating agent is a single olefin or a mixture, however, theseolefins are, in some exemplary embodiments, isomerized prior to thealkylation step.

Unless otherwise specified, all percentages are in weight percent.

The Friction Modifying Agents

The friction modifying agents of the present invention comprise alkyltoluene sulfonate salts. These salts can be prepared from alkyl tolueneprecursors by methods described below.

1. The Alkyl Toluene Precursors

An alkyl toluene precursor of the present invention may be originallyderived from a conventional Friedel-Crafts reaction that alkylatestoluene with an olefin. An alkyl toluene precursor of the presentinvention may comprise an alkyl chain that is about 3 to about 50 carbonatoms long. Another alkyl toluene precursor of the present invention maycomprise an alkyl chain that is about 10 to about 40 carbon atoms long.Yet another alkyl toluene precursor of the present invention maycomprise an alkyl chain that is about 18 to about 30 carbon atoms long.The toluene ring may be linked to any position on the alkyl chain exceptfor position 1 on the alkyl chain. As persons skilled in the art willappreciate, “position 1” on an alkyl chain refers to the carbon positionat the end of the chain. On the other hand, the alkyl chain can belinked to the toluene ring at any carbon position, except for theposition at which the methyl group of the toluene is attached.

The olefin that is used to alkylate the toluene can be a single olefinor a mixture of various olefins, although the latter is typically thealkylation agent of choice. Regardless whether a single olefin or amixture is used to alkylate the toluene, the olefins are preferablyisomerized. They may be isomerized prior to, during, or after thealkylation step, but are preferably isomerized prior to the alkylationstep. At least about 0.5%, more preferably, about 1% to about 50%, andparticularly preferably, about 1.5% to about 35% of the olefins in thealkylation agent are alpha olefins. In an exemplary friction modifyingagent of the present invention, the alpha olefin content is about 10%.In another exemplary friction modifying agent of the present invention,the alpha olefin content is about 16%. On the other hand, the olefins inthe alkylation mixture may be branched or unbranched, but are preferablynot entirely unbranched. Preferably, about 5% to about 80% of theolefins are branched, more preferably, about 10% to about 60% of theolefins are branched, and particularly, about 14% to about 31% of theolefins are branched. In an exemplary friction modifying agent of thepresent invention, about 14% of the olefins in the mixed-olefinalkylation agent are branched. In another exemplary friction modifyingagent of the present invention, about 25% of the olefins in themixed-olefin alkylation agent axe branched. In yet another exemplaryfriction modifying agent of the present invention, about 30% of theolefins in the mixed-olefin alkylation agent are branched.

Methods of isomerizing olefin are known. Persons skilled in the arttypically use one of at least two types of acidic catalysts for thispurpose. Specifically, the acidic catalysts can be solid or liquid. Anumber of known solid acidic catalysts may be suitable, but a solidcatalyst having at least one metal oxide is preferred. The metal oxidecan be one selected from: natural zeolites, synthetic zeolites,synthetic molecular sieves, and clays. Preferably, the solid acidiccatalyst comprises the acid forms of an acidic clay, or an acidicmolecular sieve, or a zeolite having an average pore size of at least6.0 angstroms. Useful acidic clays, including, for example,montmorillonite, laponite and saponite, may be derived fromnaturally-occurring or synthetic materials. Pillared clays may alsoserve as alkylation catalysts. Other molecular sieves withone-dimensional pore systems, having average pore sizes of less than 5.5angstroms, may also serve as acidic catalysts. Examples include SM-3,MAPO-11, SAPO-11, SSZ-32, ZSM-23, MAPO-39, SAPO-39, ZSM-22, SSZ-20,ZSM-35, SUZ-4, NU-23, NU-86, and natural or synthetic ferrierites. Thesecatalysts are described, for example, in HANDBOOK MOLECULAR SIEVES byRosamarie Szostak (New York, Van Norsrand Reinhold, 1992), and in U.S.Pat. No. 5,282,858, which are hereby incorporated by reference.

The isomerization process can be carried out, for example, attemperatures ranging from about 50° C. to about 280° C. Because olefinstend to have high boiling points, the process is preferably carried outin the liquid phase, in batch or continuous mode. In the batch mode, astirred autoclave or glass flask, which may be heated to the desiredreaction temperature, is typically used. On the other hand, a continuousprocess is most efficiently carried out in a fixed-bed process. In afixed-bed process, space rates, which measure the rates of contactbetween the reactants and the catalyst beds, can range from about 0.1WHSV to about 10 or more WHSV (i.e., weight of reactant feed per weightof catalyst per hour). The catalyst is charged into the reactor, whichcan be heated to the desired reaction temperature. The olefin can alsobe heated before it is exposed to the catalyst bed. An exotherm of about10° C. to about 15° C. is often observed along the catalyst bed. Thereactor effluent containing partially-branched and isomerized olefin isthen collected. In both batch and continuous modes, the resultingpartially-branched and isomerized olefin mixture-typically contains acertain olefin distribution (alpha-olefin, beta-olefin, internal-olefin,trisubstituted olefin and vinylidene-olefin) and branching content,which can be differentiated from the non-isomerized olefin.

Persons skilled in the art are able to choose isomerization conditionsunder which particular levels of isomerization may be achieved.Specifically, the level of isomerization is typically characterized bythe amount of alpha olefins and the level of branching in a particularolefin sample or mixture. The amount of alpha olefin and the level ofbranching can in turn be determined using various conventional methods,including, for example, Fourrier Transformed Infra Red (FTIR)spectroscopy. In a typical FTIR spectroscopy method, the level (orpercentage) of alpha olefins can be measured by following the absorbanceof a particular sample at 910 cm⁻¹ and comparing it to the 910-cm⁻¹absorbance of calibration samples with known alpha olefin levels. Thelevel (or percentage) of alpha olefin in the calibration samples can beobtained, for example, from ¹³C quantitative nuclear magnetic resonance(NMR) spectroscopy according to known protocols.

The percentage of branching can also be measured by FTIR spectroscopy byfollowing the absorbance of a sample at 1378 cm⁻¹. This absorbancecorresponds to the extent of deformation vibration of methyl groups. Theabsorbance of an isomerized olefin sample is then compared to the1378-cm⁻¹ absorbance of a set of calibration samples with knownbranching levels. Typically, a particular olefin mix to be tested isfirst hydrogenated, converting the unbranched portion to n-alkanes andthe branched portion to branched alkanes. Gas chromatography is thenused to distinguish the unbranched n-alkanes from the branched alkanes,the proportion of which correlates to the percent branching level inthat olefin mix.

To achieve the desired levels of isomerization in a particular olefinmixture, a person skilled in the art can also mix olefins of differentbut known isomerization levels. For example, the skilled person may mix8 portions of a 45%-branched olefin mix A comprising 15% alpha olefins,with 2 portions of a 25%-branched olefin mix B comprising 5% alphaolefins, to achieve a mixture AB that is 41%-branched and comprising 13%alpha-olefins.

As described above, the olefins used to alkylate toluene in the presentinvention comprise at least about 0.5%, more preferably, about 1% toabout 50%, and particularly preferably, about 1.5% to about 35%, alphaolefins. Suitable-olefins in this regard may be about 5% to about 80%branched, more preferably, about 10% to about 60% branched, andparticularly preferably, about 14% to about 31% branched.

The alkylation step of the present invention may take place prior to,simultaneously with, or after, the isomerization step. It is howeverpreferred that the isomerization step occurs before the alkylation step,so that the olefins that are used to alkylate toluene compriseisomerized olefins.

Various known alkylation methods can be used to make the alkyl tolueneprecursors. For example, a typical alkylation reaction, which takesplace in the presence of a hydrogen fluoride catalyst, may competentlyserve this purpose. A high toluene-to-olefin charge/molar ratio, forexample, at about 10, is used in a single reactor in order to increasethe alkylation rate vs. isomerization and dimerization rate, yielding areaction product that comprises a high level of monoalkyl toluene.Various other methods can also be used to achieve alkylation, but nearlyalways, a one-stage reactor is used as the preferred vessel in which thereaction would take place.

The alkylation process typically takes place at a temperature rangingfrom about 20° C. to about 250° C. Similar to the isomerization processdiscussed above, the alkylation process is preferably carried out in aliquid phase to accommodate the liquid olefins at these temperatures.The alkylation process may be activated in batch or continuous mode,with the former mode being carried out in a heated and stirred autoclaveor glass flask, and with the latter mode carried out in a fixed-bedprocess.

In the fixed bed process, the catalyst is heated to the desired reactiontemperature, for example, at about 100° C. to about 200° C. Pressure isincreased by means of a back pressure valve so that the pressure isabove the bubble point pressure of the toluene at the reactiontemperature. After pressurizing the system to the desired pressure, thetemperature is then increased to the desired reaction temperature.Alternatively, toluene may be introduced into die reactor at reactiontemperature. A flow of the olefin is then introduced into the flow oftoluene before the mixture comes into contact with the catalyst bed.Regardless of the mode in which the alkylation reaction is carried out,the reactor effluent typically contains alkyltoluene, mixed with excesstoluene. The excess toluene can be removed by distillation, strippingevaporation under vacuum, or other means known to those skilled in theart.

2. The Alkyl Toluene Sulfonate Salts

The alkyl toluene sulfonate salts of the present invention arerepresented by the general formula:

wherein R₁ is a metal sulfonate group, and R₂ is an alkyl group.Moreover, the alkyl toluene sulfonate salts of the present invention areoil-soluble.

These salts are derived from alkyl toluene sulfonic acids, which can beprepared by sulfonating the alkyl toluene precursors. Specifically, thealkyl toluene precursors described above may be sulfonated inconventional ways, such as using a SO₃/Air Thin Film Sulfonation method.Applying that method, the alkyl toluene precursor is mixed with aSO₃/Air falling film made by CHEMITHON® or BALLESTRA®.

The sulfonate salts of the present invention can be prepared by methodsknown to those skilled in the art. For example, they may be obtained byreacting alkyl toluene sulfonic acids with sources of suitable metals.An exemplary method comprises combining a reactive base of a metal, suchas a hydroxide, with an alkyl toluene sulfonic acid. This isconventionally carried out in the presence of a hydroxylic promoter suchas water; alcohols such as 2-ethyl hexanol, methanol, or ethyleneglycol; and typically in an inert solvent, in which the resultingsulfonate salts may be dissolved. The reaction mixtures are typicallyheated. After the reactive bases of the metals are converted into themetal sulfonates, the reaction promoters and solvents can be removed bydistillation and other conventional methods.

The metals that form the alkyl toluene sulfonate salts of the presentinvention may be any known metals that are capable of forming salts withalkyl toluene sulfonic acids. In a particular embodiment of the presentinvention, the metal is an alkali metal or an alkaline earth metal. Theterm “alkaline earth metal” refers to calcium, barium, magnesium andstrontium. The term “alkali metal” refers to lithium, sodium, potassium,rubidium, cesium and francium. In a further embodiment of the presentinvention, the metal is an alkaline earth metal. In yet another specificembodiment of the present invention, the metal is calcium.

The alkyl toluene sulfonate salts of the present invention may be eitherneutral or overbased salts. Overbased materials are characterized by ametal content in excess of that which would be present according to thestoichiometry of the metal cation in the sulfonate said to be overbased.The term “base number” or “BN” refers to the amount of base equivalentto milligrams of KOH in one gram of sample. Thus, a higher BN reflectsmore alkaline products and thus a greater alkalinity reserve. The BN ofsamples can be determined by a variety of methods, including, forexample, ASTM test No. D2896 and other equivalent procedures. The term“total base number” or “TBN” refers to the amount of base equivalent tomilligrams of KOH in one gram of functional fluid. These terms are oftenused interchangeably with “base number” or “BN,” respectively. The term“low overbased” refers to a BN or TBN of about 2 to about 60. The term“high overbased” refers to a BN or TBN of about 60 or more.

The alkyl toluene sulfonate salts of the present invention may be eitherneutral or overbased salts. Accordingly, they may have a TBN of about 0to about 400. The alkyl toluene sulfonate salts of the present inventionare preferably overbased to provide a TBN of about 2 to about 400, andpreferably highly overbased to have a TBN of between about 60 to about400, more preferably about 220 to about 380, and particularly preferablyabout 280 to about 350. An exemplary alkyl toluene sulfonate salt oftile present invention is highly overbased with a TBN of about 320.

Methods and reaction conditions for overbasing are known in the art, forexample, as generally disclosed in U.S. Pat. No. 3,496,105, which isincorporated herein by reference to the extent it does not conflict withthe disclosures and the claims herein. For the present invention, theoverbasing may be carried out with carbon dioxide. It is believed thatthe carbon-dioxide treatment may lead to the formation of a colloidaldispersion of metal base. Typically, the overbased salts of the presentinvention are formed in the presence of methanol and xylene, and in theabsence of chlorine.

The alkyl toluene sulfonate salts of the present invention are useful asadditives in functional fluids in amounts sufficient to provide thedesired frictional properties to the fluids, and to improve brake andclutch capacities in machines housing those fluids. Typically, at leastabout 0.15 wt. % of a single alkyl toluene sulfonate salt or a mixtureof such salts is used in a finished functional fluid of the presentinvention. In various embodiments of the present invention, the amountof sulfonates in the finished functional fluid may range from about 0.15wt. % to about 4.0 wt. %, or from about 0.5 wt. % to about 3.5 wt. %, orfrom about 1.5 wt. % to about 2.5 wt. %. An exemplary finishedfunctional fluid of the present invention comprises about 1.8 wt. % of acertain alkyl toluene sulfonate salt mixture.

The Functional Fluids

The functional fluid of the present invention comprises one or more baseoils, which are present in major amounts (i.e., an amount greater thanabout 50 wt. %). Generally, the base oil or the mixture of base oils ispresent in an amount greater than about 60 wt. %, or greater than about70 wt. %, or greater than about 80 wt. %, based on the total mass of thefunctional fluid. An exemplary functional fluid of the present inventioncomprises about 88 wt. % of a mixture of base oils.

The base oils may be derived from mineral oils, synthetic oils orvegetable oils. A base oil having a viscosity of at least about 2.5 cStat about 40° C. and a pour point at or below about 20° C., preferably ator below about 0° C., is desirable. The base oils may be derived fromsynthetic or natural sources. Suitable base oils may be selected fromany one or combination of Group I through Group V base stocks as definedin American Petroleum Institute Publication 1509, which is hereinincorporated by reference. Suitable base oils may also include variousnewly developed base stocks, for example, those that are informallyreferred to as Group I/+, Group II/+, or Group III/+, as well as otherbase stocks that are currently used by skilled persons in the art.General descriptions of these newly developed base stocks can be foundin various places, for example, at Chevron's products/base oils website(www.chevron.com/products/prodserv/BaseOils/gf4_faq.shtml).

Natural base oils may include, for example, mineral oils and vegetableoils. Mineral oils suitable for use as the base oil of this inventioninclude, for example, paraffinic, naphthenic and other oils that areordinarily used in lubricating oil compositions. Suitable vegetable oilsmay include, for example, canola oil or soybean oil.

Synthetic oils of proper viscosity include, for example, hydrocarbonsynthetic oils, synthetic esters, and mixtures thereof. Hydrocarbonsynthetic oils may include, for example, oils prepared from thepolymerization of ethylene, higher olefins, examples of which includepolyalphaolefin or PAO, or from hydrocarbon synthesis procedures usingcarbon monoxide and hydrogen gases such as in a Fisher-Tropsch process.Useful synthetic hydrocarbon oils include liquid polymers of alphaolefins having the proper viscosity. Especially useful are thehydrogenated liquid oligomers of C₆ to C₁₂ alpha olefins such as1-decene trimer. Likewise, alkyl benzenes of proper viscosity, such asdidodeeyl benzene, can be used. Useful synthetic esters include estersof monocarboxylic acids and polycarboxylic acids, as well asmono-hydroxy alkanols and polyols. Typical examples are didodeeyladipate, pentaerythritol tetracaproate, di-2-ethylhexyl adipate,dilaurylsebacate, and the like. Complex esters prepared from mixtures ofmono- and dicarboxylic acids and mono- and dihydroxy alkanols can alsobe used. Blends of mineral oils with synthetic oils are likewisepotentially useful.

An exemplary functional fluid of the present invention employs a mixtureof two Group I base oils, EXXON MOBIL® AP/E CORE™ 150N and EXXON MOBIL®AP/E CORE™ 600N.

A functional fluid of the present invention contains afriction-modifying amount of one or more alkyl toluene sulfonate saltsas described herein. Typically, at least about 0.15 wt. % of one or morealkyl toluene sulfonate salts are included in a functional fluid of thepresent invention. Preferably, the concentration of alkyl toluenesulfonate salts in the functional fluid ranges from about 0.15 wt. % toabout 4.0 wt. %, more preferably from about 0.5 wt. % to about 3.5 wt.%, and particularly preferably from about 1.5 wt. % to about 2.5 wt. %.An exemplary functional fluid of the present invention comprises about1.8 wt. % of an alkyl toluene sulfonate salt mixture.

Besides the alkyl toluene sulfonate salts of the present invention, thefunctional fluid may comprise other additives as described below. Theseadditional components can be blended in any order and can be blended ascombinations of components. The following additive components areprovided as examples of components that may be favorably employed,without limiting the scope of the present invention.

Various dispersants may be added to the functional fluids of the presentinvention. Dispersants, and typically those of the ashless (metal-free)kinds are typically used in lubricants and functional fluids to maintainin suspension insoluble materials resulting from oxidation during use,thus preventing sludge flocculation and precipitation, or deposition onmetal parts. An ashless dispersant generally comprises an oil-solublepolymeric hydrocarbon backbone having functional groups that are capableof associating with particles to be dispersed. Many types of ashlessdispersants are known in the art, including amines, alcohols, amides, orester polar moieties attached to the polymer backbones via bridginggroups. The ashless dispersants of the present invention may be chosenfrom, for example, oil-soluble salts, esters, amino-esters, amides,imides, and oxazolines of long-chain hydrocarbon-substituted mono anddicarboxylic acids or their anhydrides, thiocarboxylate derivatives oflong-chain hydrocarbons, long-chain aliphatic hydrocarbons having apolyamine attached directly thereto; and Mannich condensation productsformed by condensing a long-chain substituted phenol with formaldehydeand polyalkylene polyamine. Examples of suitable ashless dispersants mayinclude “carboxylic dispersants,” which are reaction products ofcarboxylic acylating agents (acids, anhydrides, esters, etc.) comprisingat least 34 and preferably at least 54 carbon atoms withnitrogen-containing compounds (such as amines), organic hydroxylcompounds (such as aliphatic compounds including monohydric andpolyhydric alcohols, or aromatic compounds including phenols andnephthols), and/or basic inorganic materials. Succinimide dispersantsare a species of carboxylic dispersants, which may be produced byreacting hydrocarbyl-substituted succinic acylating agent with organichydroxyl compounds, or with amines comprising at least one hydrogen atomattached to a nitrogen atom, or with a mixture of the hydroxyl compoundsand amines. Examples of suitable ashless dispersants also include, forexample, amine dispersants, which are reaction products of relativelyhigh molecular weight aliphatic halides and amines, preferablypolyalkylene polyamines. Examples thereof have been described, forexample, in U.S. Pat. Nos. 3,275,554, 3,438,757, 3,454,555, 3,565,804,and the like. Examples of suitable dispersants also include, forexample, “Mannich dispersants,” which are the reaction products of alkylphenols in which the alkyl group contains at least 30 carbon atoms withaldehydes (especially formaldehyde) and amines (especially polyalkylenepolyamines). These dispersants have been described, for example, in U.S.Pat. Nos. 3,036,003, 3,586,629, 3,591,598, 3,980,569, and the like.Suitable ashless dispersants may even include post-treated dispersants,which can be obtained by reacting carboxylic, amine or Mannichdispersants with reagents such as dimercaptothiazoles, urea, thiourea,carbon disulfide, aldehydes, ketones, carboxylic acids,hydrocarbon-substituted succinic anhydrides, nitrile epoxides, boroncompounds and the like. Post-treated dispersants have been described,for example, in U.S. Pat. Nos. 3,329,658, 3,449,250, 3,666,730, and thelike. Suitable ashless dispersants may also include polymericdispersants, such as those described in, for example, U.S. Pat. Nos.3,329,658, 3,449,250, 3,666,730, and the like. The disclosures of theherein patents, to the extent they do not conflict with the disclosuresand claims herein, are incorporated in their entirely by reference.

Metal-containing detergents may be added to the functional fluids of thepresent invention. Such detergents may include, for example, sulfurizedor unsulfurized alkyl or alkenyl phenates, sulfonates derived fromsynthetic or natural feedstocks, carboxylates, salicylates, phenalates,sulfurized or unsulfurized metal salts of multi-hydroxy alkyl or alkenylaromatic compounds, alkyl or alkenyl hydroxy aromatic sulfonates,sulfurized or unsulfurized alkyl or alkenyl naphthenates, metal salts ofalkanoic acids, metal salts of an alkyl or alkenyl multiacid, andchemical or physical mixtures thereof. Such metal-containing detergentsmay be overbased or neutral. Overbased metal-containing detergents maybe high-overbased or low-overbased.

Antioxidants are optionally added to the functional fluids to reduce thetendency of mineral oils to deteriorate in service. Such deteriorationmay otherwise lead to deposits of sludge and varnish-like debris onmetal surfaces. The oxidation deterioration may also lead to anunacceptable increase in viscosity in the fluids, impairing theperformance of the machines that house the functional fluid, and/ordamaging the relatively moving and coupling parts. Many antioxidants areknown in the art, including, for example, phenol-type (phenolic)oxidation inhibitors, such as4,4′-methylene-bis(2,6-di-tert-butylphenol),4,4′-bis(2,6-di-tert-butylphenol),4,4′-bis(2-methyl-6-tert-butylphenol),2,2′-methylene-bis(4-methyl-6-tert-butylphenol),4,4′-butyldene-bis(3-methyl-6-tert-butyl phenol),4,4′-isopropylidene-bis(2,6-di-tert-butylphenol),2,2′-methylene-bis(4-methyl-6-nonylphenoI),2,2′-isobutylidene-bis(4,6-dimethylphenol),2,2′-methylene-bis(4-methyl-6-cyclohexylphenol),2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6-tert-butyl-phenol,4,4′-thiobis(2-methyl-6-tert-butylphenol),2,2′-thiobis(4-methyl-6-tert-butylphenol), andbis(3,5-di-tert-butyl-4-hydroxybenzyl). Antioxidants may also be of thediphenylamine-type, which include, for example, alkylated diphenylamine,phenyl-α-naphthylamine, and alkylated-α-naphth-ylamine. Other types ofoxidation inhibitors may include, for example, metal dithiocarbamate(e.g., zinc dithiocarbamate), methylene bis-(dibutyldithiocarbamate),and the like.

One or more anti-wear/extreme pressure agents may be included in thefunctional fluid compositions of the present invention, especially whenthe fluids are blended for use in heavy-duty machines such as farmtractors. As their name implies, these agents reduce wear of movingmetallic parts. Examples of such agents include phosphates, carbamates,esters, sulfur-containing compounds, molybdenum complexes, zincdialkyldithiophosphate (primary alkyl-, secondary alkyl-, andaryl-types), sulfurized oils, sulfurized isobutylene, sulfurizedpolybutene, methyl trichlorostearate, chlorinated naphthalene,fluoro-alkylpolysiloxane, and lead naphthenate.

One or more rust inhibitors may also be added to the functional fluid.These agents typically fall into two broad categories: nonionicpolyoxyethylene surface active agents, and other compounds. Nonionicpolyoxyethylene surface active agents include, for example,polyoxyethylene lauryl ether, polyoxyethylene higher alcohol ether,polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether,polyoxyethylene octyl stearyl ether, polyoxyethylene oleyl ether,polyoxyethylene sorbitol monostearate, and polyethylene glycolmonooleate. Other rust-inhibiting compounds include, for example,stearic acid and other fatty acids, dicarboxylic acids, metal soaps,fatty acid amine salts, metal salts of heavy sulfonic acid, partialcarboxylic acid ester of polyhydric alcohol, and phosphoric ester.

It is not uncommon to include demulsifiers in functional fluids,especially when such fluids are used in environments where watercontamination is prevalent or inevitable. Typical demulsifiers include,for example, the addition product of alkylphenol and ethylene oxide,polyoxyethylene alkyl ether, and polyoxyethylene sorbitan ester.

In addition to the friction-modifying amount of alkyl toluene sulfonatesalts, the functional fluids of the present invention may optionallycomprises one or more other friction modifiers. These other frictionmodifiers may be selected from, for example, fatty alcohols, 1,2-diols,borated 1,2-diols, fatty acids, amines, fatty acid amides, boratedesters, and other esters.

As it is known in the art, many additives are multifunctional. Forexample, a particular compound may be included in the lubricating fluidto provide dispersancy in addition to antiwear properties. Suitablemultifunctional additives include, for example, sulfurized oxymolybdenumdithiocarbamate, sulfurized oxymolybdenum organo phosphorodithioate,oxymolybdenum monoglyceride, oxymolybdenum diethylate amide,amine-molybdenum complex compound, and sulfur-containing molybdenumcomplex compound.

A functional fluid of the present invention may optionally include oneor more viscosity index improvers. They include, for example,polymethacrylate-type polymers, ethylene-propylene copolymers,styrene-isoprene copolymers, hydrogenated styrene-isoprene copolymers,polyisobutylene, and dispersant-type viscosity index improvers.

For certain applications, a functional fluid of the present inventionmay also include one or more pour point depressants, including, forexample, polymethyl methacrylate.

Moreover, a functional fluid of the present invention may comprise oneor more foam inhibitors. Suitable foam inhibitors include, for example,alkyl methacrylate polymers, dimethyl silicone polymers, and likemolecules,

The functional fluid compositions of the present invention areformulated by known methods. The formulation is typically carried out atthe additive manufacturing plant or blending facility, but thecompositions can also be formulated by hand.

Often all the additives, except for the viscosity index improvers andpour point depressants, are blended into a concentrate or additivepackage that is subsequently blended into base stock to make finishedfluids. Use of such concentrates is conventional and well known. Theconcentrates are formulated to contain the additives in proper amountsso as to provide the desired concentration in the final formulation whenthe concentrate is combined with a predetermined amount of base oils.

Chloride Compatibility

There may be occasionally a need to use the friction modifying agentsand functional fluids of the present invention in the presence ofcertain amounts of chloride ions. For example, the process tomanufacture alkyl toluene sulfonate salts may itself introduce chlorideions into the environment wherein a friction modifying agent of thepresent invention is used because one or more chloride-containingcompounds may be added to modify viscosity during that process. Having aclass of friction modifying agents that can be used in the presence ofchloride ions is therefore desirable as such friction modifying agentscan be used without necessarily removing the chloride ions.

The friction-modifying capacities of the alkyl toluene sulfonate saltsand functional fluids of the present invention are not substantiallydiminished in the presence of chloride ions. Accordingly, otheradditives and the base oils in these functional fluids are likewisecompatible with the presence of chloride. Typically, thefriction-modifying capacities of the alkyl toluene sulfonate salts andfunctional fluids of the present invention are not substantiallydiminished in the presence of up to about 10 ppm, preferably up to about20 ppm, and particularly preferably up to about 50 ppm of chloride ions.In an exemplary embodiment, the presence of about 50 ppm of chloridedoes not substantially diminish the friction-modifying capacity of acertain functional fluid prepared according to the specifications of thepresent invention. For purposes of the present invention, the term “notsubstantially diminish” refers to a reduction of not more than 5%, 10%,20%, or 30% of friction-modifying capacity. Accordingly, chloride ionsare said to not substantially diminish the friction-modifying capacityof a certain alkyl toluene sulfonate salt/mixture or a functional fluidwhen its friction-modifying capacity in the presence of chloride is atleast about 70%, about 80%, about 90%, or about 95%, of itsfriction-modifying capacity in the absence of chloride.

This invention will be further understood by reference to the followingexamples, which axe not to be considered as limitative of its scope.

EXAMPLES

The following examples are provided to illustrate the present inventionwithout limiting it. While the present invention has been described withreference to specific embodiments, this application is intended toencompass those various changes and substitutions that may be made bythose skilled in the art without departing from the spirit and scope ofthe appended claims.

Example 1 Improving Static Breakaway Friction Values

Various finished functional fluid samples were prepared. Theirfriction-modifying capacities were measured in a static breakawayfriction bench test designed to simulate the conditions under which aset of wet brakes or wet clutches may operate. The device in which thetests were carried out comprised a brake disc, which was lubricated inan open oil sump with Functional Fluid Samples 1 to 10 and ComparativeFunctional Fluid A, which are listed below in Table 3. The devicefurther comprised friction pads, which were in contact with the brakedisc, and a shaft that rotated the brake disc. During each test, acertain level of pressure was applied on the friction pads, and anelectric motor drove the shaft to rotate while the brake disc was heldin its original position. At a particular pressure level, a reading ofmaximum resisting torque reached within 0.25 seconds after the shaftstarts to rotate was recorded. Ten of these 0.25-second cycles werecarried out at each pressure level. An average was taken from the 10maximum torque readings, yielding a 10-round average maximum torque,which was then divided by the level of pressure to arrive at a staticbreakaway friction value.

The Negative Control Sample comprised an alkyl benzene sulfonate insteadof an alkyl toluene sulfonate mixture of the present invention, in anamount that provided the same concentration of Ca²⁺ as in the FunctionalFluid Samples and Comparative Fluid Sample A. The increase in staticbreakaway friction values were determined by subtracting the staticbreakaway friction values of the Negative Control Sample [Y] from thevalues of the Functional Fluid Samples and Comparative Fluid Sample A[X], Functional Fluid Samples 1 to 10 and Comparative Fluid Sample Aexhibited significant increase in static breakaway friction values.

Olefins of various branching/isomerization levels (Olefins I to VIII inTable 1) were mixed to prepare the alkylation agents (the “olefin mixes”in Table 2). These olefin mixes were then used to prepare alkyl toluenes(ATs I to X in Table 2). To prepare the Comparative Package A,non-isomerized Olefin(comp) (Table I) was used to alkylate toluene,yielding AT(comp) (Table 2). To prepare the Negative Control package,the same, non-isomerized Olefin(comp) (Table 1), was used to alkylatebenzene, yielding AB(−) (Table 2). These alkylated precursors weresulfonated by conventional methods such as the SO₃/Air Thin FilmSulfonation method described herein. The sulfonation products were thenintroduced to additive packages at concentrations that would provideabout the same amount of Ca²⁺ to the fluids. Other components of theadditive packages are also listed in Table 2.

All sulfonation products, including the ones comprising the AB(−) andthe AT(comp), were highly overbased to give a TBN of about 320.

TABLE 1 The Olefins Alpha-Olefin Olefin # Carbon Numbers BranchingLevels Concentrations Olefin I 20–24 20.4% 12.1% Olefin II 20–26 54.8% 1.6% Olefin III 20–24 25.0%  1.1% Olefin IV 20–26 23.4% 31.9% Olefin V20–24 21.2%  5.6% Olefin VI 20–24 17.5% 12.0% Olefin VII 20–26 20.7%11.7% Olefin VIII 20–26 0 Non-isomerized Olefin(comp) 20–24 0Non-isomerized

TABLE 2 The Alkylation Agents & Friction Modifying Agents PackagesAdditive Sulfonate Branch Package # (wt. %) AT # Olefin mixes (%)Optional Components 1 1.8 I  80% Olefin I 27.3 Examples** of optional 20% Olefin II components that can be 2 1.8 II  80% Olefin I 21.0favorably employed in the  20% Olefin IV packages, selected from one or3 1.8 III  80% Olefin III 31.0 more of:  20% Olefin II a) antioxidants;4 1.8 IV  80% Olefin III 24.7 b) anti-wear/extreme pressure  20% OlefinIV agents; 5 1.8 V 100% Olefin V 21.2 c) detergents 6 1.8 VI  80% OlefinV 17.0 d) rust inhibitors;  20% Olefin VIII e) non-alkyl toluenesulfonate 7 1.8 VII 100% Olefin VI 17.5 friction modifiers; 8 1.8 VIII 90% Olefin VI 15.8 f) multi-functional additives;  10% Olefin VIII g)foam inhibitors; 9 1.8 IX  80% Olefin VI 14.0 h) demulsifiers;  20%Olefin VIII i) dispersants; 10  1.8 X 100% Olefin VII 20.7 j) sealconditioning agents Comp. 1.8 AT Olefin(comp) 0 Pack. A (comp) Negative1.9* AB(−) Olefin(comp) 0 Control Package *The alkyl benzene sulfonatein the Negative Control package (i.e., 1.9 wt. %) provided an equivalentamount of Ca²⁺ to the package as did the alkyl toluene sulfonates in theother packages (i.e., 1.8 wt. %). **The optional components listed inthis column are merely examples of the type of components that can beemployed for purpose of the present invention. They are listed herein toillustrate the claimed invention without limiting it.

The Additive Packages of Table 2 were further blended with-a certainmixture of base oils, one or more viscosity improvers, and one or morepour point depressants. The finished functional fluids and theircomponents are listed in Table 3.

TABLE 3 Components of the Finished Functional Fluids Functional AdditivePackage Fluid # (6.85 wt. %) Other Components 1–10 1–10 Viscosity IndexImprover  4.75 wt. % Comp. Comp. Pour Point Depressant  0.20 wt. %Functional Pack. A EXXON MOBIL ® AP/E 54.70 wt. % Fluid A Core ™ 150NEXXON MOBIL ® AP/E 33.50 wt. % Core ™ 600N

Static breakaway friction values were determined. Each sample orcomparative sample (value [X]) was measured in parallel with a negativecontrol sample (value [Y]) to account for experimental variability. Theresults for Functional Fluid samples 1 to 10 and Comparative FunctionalFluid A are listed in Table 4.

TABLE 4 Test Results Static Increase in Static Breakaway StaticBreakaway Breakaway Friction Friction Values Friction of Negative ValuesSample # (mm³) = [X] Control (mm³) = [Y] (mm³) = [X] − [Y] 1 17463 17010453 2 17617 17010 607 3 17653 17010 643 4 17340 17010 330 5 17869 17110759 6 17364 16924 440 7 17951 16881 1070 8 16555 15965 590 9 16923 15965958 10  16638 15965 673 Comp. 17766 17441 325 Functional Fluid A

Example 2 Chloride Compatibility

Chloride compatibility of a friction modifying agent, i.e., an alkyltoluene sulfonate salt made from alkyl toluene precursor (AT) XI, and afunctional fluid, i.e., Functional Fluid Sample 11, was determined usingComparative Functional Fluid B. Components of these samples are listedin Table 5. Alkyl toluene precursor (AT) XI had a branching level ofabout 20.7% and an alpha olefin content of about 11.7%.

A static breakaway value of a Negative Control fluid comprising aCa²⁺-equivalent amount of alkyl benzene sulfonate instead of alkyltoluene sulfonate was obtained in parallel with Functional Fluid Sample11 and Comparative Functional Fluid B. This value was then subtractedfrom the static breakaway values of the samples to yield the “staticbreakaway friction increases” results in Table 5.

Functional Fluid Sample 11 and Comparative Functional Fluid B bothshowed higher breakaway friction values than the Negative Control fluid,suggesting that these fluids both had improved frictional properties.The presence of chloride in Fluid Sample 11 did not substantiallydiminish the friction-modifying capacity of the alkyl toluene sulfonatesalts in that fluid.

TABLE 5 Functional Fluid Sample 11 Comparative Functional Fluid B 1.8wt. % AT sulfonate XI (20.7% branched) 1.8 wt. % AT sulfonate XI (20.7%branched) Package comprises the same optional components as inFunctional Fluid Sample 11 and at the same Package may also optionallycomprise one or concentration, which may one or more more of thefollowing components:* selected from:* a) antioxidants; a) antioxidants;b) anti-wear/extreme pressure agents; b) anti-wear/extreme pressureagents; c) rust inhibitors; c) rust inhibitors; d) detergents; d)detergents; e) non-alkyl toluene sulfonate friction modifiers; e)non-alkyl toluene sulfonate friction modifiers; f) foam inhibitors f)foam inhibitors g) dispersants; g) dispersants; h) demulsifiers; h)demulsifiers; i) multi-functional additives; and i) multi-functionaladditives; and j) seal conditioning agents. j) seal conditioning agents.50 ppm Cl⁻ 0 ppm Cl⁻ Other components in the functional fluid: Othercomponents in the functional fluid: a) 0.20 wt. % pour point depressanta) 0.20 wt. % pour point depressant b) 4.75 wt. % 94 viscosity indeximprover b) 4.75 wt. % viscosity index improver c) ~88 wt. % EXXONMOBIL ® AP/E CORE ™ c) ~88 wt. % EXXON MOBIL ® AP/E CORE ™ Base Oils(mixed) Base Oils (mixed) Static Breakaway Friction Increase = 1346 mm³Static Breakaway Friction Increase = 673 mm³ *The following is anon-limiting list of optional components that may be favorably employed.

1. A functional fluid composition comprising an admixture of: (a) amajor amount of an oil of lubricating viscosity; and (b) afriction-modifying amount of one or more oil-soluble alkyl toluenesulfonate salts, which may be represented by the formula:

wherein R₁ is a metal sulfonate group and R₂ is an alkyl group.
 2. Thefunctional fluid composition of claim 1, wherein the one or more alkyltoluene sulfonate salts are chosen from alkali metal salts and alkalineearth metal salts.
 3. The functional fluid composition of claim 2,wherein the one or more alkyl toluene sulfonate salts are alkaline earthmetal salts.
 4. The functional fluid composition of claim 3, wherein theone or more alkyl toluene sulfonate salts are calcium salts.
 5. Thefunctional fluid composition of claim 1, wherein the one or more alkyltoluene sulfonate salts are overbased salts.
 6. The functional fluidcomposition of claim 5, wherein the one or more alkyl toluene sulfonatesalts are overbased with carbon dioxide.
 7. The functional fluidcomposition of claim 1, wherein each of the one or more alkyl toluenesulfonate salts has a total base number of about 0 to about
 400. 8. Thefunctional fluid composition of claim 5, wherein each of the overbasedsalts has a total base number of about 60 to about
 400. 9. Thefunctional fluid composition of claim 8, wherein each of the overbasedsalts has a total base number of about 250 to about
 380. 10. Thefunctional fluid composition of claim 9, wherein each of the overbasedsalts has a total base number of about 300 to about
 350. 11. Thefunctional fluid composition of claim 1, wherein the one or more alkyltoluene sulfonate salts are derived from alkyl toluene precursorsprepared by reacting linear olefins with toluene.
 12. The functionalfluid composition of claim 11, wherein the linear olefins are isomerizedbefore they react with toluene.
 13. The functional fluid composition ofclaim 11, wherein each of the linear olefins is a single olefin or amixture of olefins.
 14. The functional fluid composition of claim 13,wherein the single olefin is a C₁₈ to C₃₀ linear alpha olefin.
 15. Thefunctional fluid composition of claim 13, wherein the olefins in themixture of olefins are chosen from C₁₈ to C₃₀ linear alpha olefins. 16.The functional fluid composition of claim 12, wherein about 0.5% toabout 50% of each of the linear olefins are alpha olefins.
 17. Thefunctional fluid composition of claim 16, wherein about 1.5% to about35% of each of the linear olefins are alpha olefins.
 18. The functionalfluid composition of claim 12, wherein about 5% to about 80% of each ofthe isomerized linear olefins are branched.
 19. The functional fluidcomposition of claim 18, wherein about 10 to about 60% of each of theisomerized linear olefins are branched.
 20. The functional fluidcomposition of claim 1, comprising about 0.15 wt. % to about 4.0 wt. %of the one or more alkyl toluene sulfonate salts.
 21. The functionalfluid composition of claim 20, comprising about 0.5 wt. % to about 3.5wt. % of the one or more alkyl toluene sulfonate salts.
 22. Thefunctional fluid composition of claim 21, comprising about 1.5 wt. % toabout 2.5 wt. % of the one or more alkyl toluene sulfonate salts. 23.The functional fluid composition of claim 1, further comprising one ormore additives selected from: (1) antioxidants; (2) rust inhibitors; (3)demulsifiers; (4) friction modifying agents other than alkyl toluenesulfonates; (5) viscosity index improvers; (6) multi-functionaladditives; (7) dispersants; (8) anti-wear/extreme pressure agents; (9)pour point depressants; (10) foam inhibitors; (11) detergents; and (12)seal conditioning agents.
 24. The functional fluid composition of claim1, wherein the friction-modifying capacity of the composition is notsubstantially diminished in the presence of chloride ions.
 25. Thefunctional fluid composition of claim 24, wherein the friction-modifyingcapacity of the composition is not substantially diminished in thepresence of up to about 10 ppm of chloride.
 26. The functional fluidcomposition of claim 25, wherein the friction-modifying capacity of thecomposition is not substantially diminished in the presence of up toabout 50 ppm of chloride.
 27. A friction modifying agent suitable foruse in a functional fluid, comprising one or more of oil-soluble alkyltoluene sulfonate salts, which may be represented by the formula:

wherein R₁ is a metal sulfonate group, and R₂ is an alkyl group.
 28. Thefriction modifying agent of claim 27, wherein the one or more alkyltoluene sulfonate salts are chosen from alkali metal salts and alkalineearth metal salts.
 29. The friction modifying agent of claim 28, whereinthe one or more alkyl toluene sulfonate salts are alkaline earth metalsalts.
 30. The friction modifying agent of claim 29, wherein the one ormore alkyl toluene sulfonate salts are calcium salts.
 31. The frictionmodifying agent of claim 27, wherein the one or more alkyl toluenesulfonate salts are overbased salts.
 32. The friction modifying agent ofclaim 31, wherein the one or more overbased alkyl toluene sulfonatesalts are overbased with carbon dioxide.
 33. The friction modifyingagent of claim 27, wherein each of the one or more alkyl toluenesulfonate salts has a total base number of about 0 to about
 400. 34. Thefriction modifying agent of claim 31, wherein each of the one or moreoverbased alkyl toluene sulfonate salts has a total base number of about60 to about
 400. 35. The friction modifying agent of claim 34, whereineach of the one or more overbased alkyl toluene sulfonate salts has atotal base number of about 250 to about
 380. 36. The friction modifyingagent of claim 35, wherein each of the one or more overbased alkyltoluene sulfonate salts has a total base number of about 300 to about350.
 37. The friction modifying agent of claim 27, wherein the one ormore alkyl toluene sulfonate salts are derived from alkyl tolueneprecursors prepared by reacting linear olefins with toluene.
 38. Thefriction modifying agent of claim 37, wherein the linear olefins areisomerized before they react with toluene.
 39. The friction modifyingagent of claim 38, wherein each of the linear olefins is a single olefinor a mixture of olefins.
 40. The friction modifying agent of claim 39,wherein the single olefin is a C₁₈ to C₃₀ linear alpha olefin.
 41. Thefriction modifying agent of claim 39, wherein the olefins in the mixtureof olefins are chosen from C₁₈ to C₃₀ linear alpha olefins.
 42. Thefriction modifying agent of claim 38, wherein about 0.5% to about 50% ofeach of the linear olefins are alpha olefins.
 43. The friction modifyingagent of claim 42, wherein about 1.5% to about 35% of each of the linearolefins are alpha olefins.
 44. The friction modifying agent of claim 38,wherein about 5% to about 80% of each of the isomerized linear olefinsare branched.
 45. The friction modifying agent of claim 44, whereinabout 10% to about 60% of each of the isomerized linear olefins arebranched.
 46. The friction modifying agent of claim 27, wherein thefriction-modifying capacity of the friction modifying agent is notsubstantially diminished in the presence of chloride ions.
 47. Thefriction modifying agent of claim 46, wherein the friction-modifyingcapacity of the friction modifying agent is not substantially diminishedin the presence of up to about 10 ppm of chloride.
 48. The frictionmodifying agent of claim 47, the friction-modifying capacity of thefriction modifying agent is not substantially diminished in the presenceof up to about 50 ppm of chloride.
 49. A method of achieving optimalfrictional characteristics and maintaining such characteristics in amachine comprising relatively moving and coupling parts, comprising: (a)immersing at least some of the surfaces of the relatively moving andcoupling parts in a functional fluid of claim 1; and (b) operating themachine in the presence of the functional fluid.
 50. The methodaccording to claim 49, wherein the functional fluid is selected from: atractor fluid, a tractor hydraulic fluid, a transmission fluid, and ahydraulic fluid.
 51. The method according to claim 50, wherein thefunctional fluid is a tractor hydraulic fluid.
 52. The method of claim49, wherein the functional fluid further comprising one or moreadditives chosen from: (1) antioxidants; (2) demulsifiers; (3) rustinhibitors; (4) friction modifying agents that are not alkyl toluenesulfonates; (5) pour point depressants; (6) viscosity index improvers;(7) foam inhibitors; (8) multi-functional additives; (9)anti-wear/extreme pressure agents; (10) dispersants; (11) detergents;and (12) seal conditioning agents.
 53. A method of making a functionalfluid composition comprising blending the following components; (a) anoil of lubricating viscosity; and (b) one or more oil-soluble alkyltoluene sulfonate salts, which may be represented by the formula:

wherein R₁ is a metal sulfonate group, and R₂ is an alkyl group.
 54. Themethod according to claim 53, wherein one or more additives selectedfrom: antioxidants; rust inhibitors; friction modifying agents that arenot alkyl toluene sulfonates; viscosity index improvers; demulsifiers;pour point depressants; anti-wear/extreme pressure agents;multi-functional additives; foam inhibitors; detergents; sealconditioning agents; and dispersants are further blended into thefunctional fluid composition.
 55. The method according to claim 53,wherein about 0.15 wt. % to about 4.0 wt. % of the one or more alkyltoluene sulfonate salts are blended into the functional fluidcomposition.
 56. The method according to claim 55, wherein about 0.5 wt.% to about 3.5 wt. % of the one or more alkyl toluene sulfonate saltsare blended into the functional fluid composition.
 57. The methodaccording to claim 56, wherein about 1.5 wt. % to about 2.5 wt. % of theone or more alkyl toluene sulfonate salts are blended into thefunctional fluid composition.